METHOD AND CIRCUIT FOR REDUCING SPARKLE ARTIFACTS, WITH LOW-BRIGHTNESS SLEW RATE LIMIT

摘要

PURPOSE: A method and a circuit for reducing sparkle artifacts with low-brightness slew rate limit is provided to reduce sparkle artifacts in a liquid crystal imager, caused by declination, without degrading high-resolution definition of a final display. CONSTITUTION: A video signal is decomposed into a higher brightness level signal and a lower brightness level signal(12). The threshold between higher and lower brightness levels is adjustable and related to the transition between lower and higher gain portions of the gamma table for an associated liquid crystal imager. The lower brightness level signal is slew rate limited to reduce the difference in brightness between adjacent pixels(22). The higher brightness level signal is delayed in time to match the processing delay through the slew rate limiter(24). The delay matched signal and the slew rate limited signal are combined to form a modified video signal less likely to result in sparkle artifacts in the imager(26). Sparkle reduction processing is applied to luminance signals and to video drive signals in various combinations, based on independently selected thresholds.